Process of and apparatus for balancing rotative bodies



B. L. NEWKIRK FROCESS OF AND APPARATUS FOR BALANCING ROTATIVE BODIESOct. 13, 1 2 1,557,268

Filed July 25. 1920 s sheets sh eet 1 I //4 /&

- Patented Oct. 13,1925.

. {UNITEDAS'TATES PATENT. OFFICE,

BURT I1. NE'WKIRK, F MINNEA POLIS, MINNESOTA, ASSIGNOR, I BY MESNEASSIGN- MEN'IS, '10 PRECISION BALANCING MACHINE COMPANY, OF EAU CLAIRE,WIS- CONSIN, A CORPORATION OF WISCONSIN.

PROCESS OF AND APPARATUS FOR BALANCING ROTATIVE BODIES;

Application filed July 23, 1920. Serial No. 398,584.

To all whorrt it may concern:

Be it known that I, BURT L. NEW/KIRK, a

citizen of the United States, residing at 'Min'neapolis, county ofHennepin, and State of Minnesota, have invented certain new and usefulImprovements in Processes of and This novel process also provides forthe determination of resultant unbalance in two selected planes situatedat right angles to.

the axis of rotation, without an. unbalance in one plane affecting theunbalance in the other. Therefore. in quantity production of machineparts to be balanced, for example, the corrective data regarding theunbalance in the work can be marked and the correc- 'tive operationlater carried out.

In carrying out this process a novel apparatus is employed and, includedin this process, is a process for the calibration of the apparatus, theprovision of a process chart indicative of the proper positioning of thecorrective weight, and the provision of another process chartdeterminative of unbalance corrections when all factors contribut ve tothe unbalance are unknown.

- When the expression unbalance in one plane is employed. it is to beunderstood to mean that condition of unbalance of the body which can becorrected by removal or addition of material in that plane.

It is generally understood that a rotative body, when in unbalancedcondition, sets up vibrations in its supporting means and also that eachsupporting means has a natural and inherent vibration frequency under agiven Weight and distribution of mass; and, further, it is generallysupposed that when the frequency of the vibrations or oscilla- --tionsinduced by the unbalanced rotative body is .in synchronism with thenatural vibration frequency of its associated supporting means, whichcondition is designated as" critical speed, the maximum amplitude ofv1brat1on or oscillation of the supporting means is attained.

A present known method of employing this physical phenomenon is torotate a body at constant speed in a frame mounted so that itsoscillation is controlled by springs. These springs are changed until aspring is found which has a natural period of vibratlon which respondsto the particular speed of rotation of the body.

Besides being ditficult to maintain the rotative body at uniform andexact speed, another inherent disadvantage of the present processes ormethods wherein the rotative body is made to run at a constant rate ator near the critical speed and the amount of unbalance roughly estimatedfrom oscillation, is that such processes are uncertain and tedious inapplication because of the practical difliculty of maintaining constantspeed of rotation of the body, and of bringing the body back again tothe identical constant speed after stoppage to add corrective weights.In this connection, it is to be noted that slight variations in thespeed of the body, when the body is revolving at or near-the criticalspeed result in great variations in the oscillation of the frame. Avariation of this known method is to rotate the body at varying speed byincreasing or decreasing the driving power so that the criti cal speedis passed through both increasing and decreasing, butwithout means tocontrol closely the rate of passing throu h critical speed to make suchrate repeatab e, and without suflicient care to eliminate dampingeffects that influence the vibration of the supporting means. Under suchcirquently, the operator must proceed by a procumstances the amplitudeof vibration of peatable, but not unless so controlled; The

I longed succession of trials which become increasingly uncertain as thebody, by successive corrections, becomes more nearly balanced. Thesedisadvantages are all overcome by the employment of this novel process.This process is systematic and gives an accuratemeasure of the unbalanceof a rotative body. Where extreme refinement is necessary this can beaccomplished with certainty by a repetition of the process withoutexcessive expenditure of time.

Other objects of the invention will more fully appear from the followingdescription and the accompanying drawings and will be pointed out in theannexed claims.

The accompanying drawings diagrammatically disclose a structure designedto carryout the objects of the invention, but

it is to be understood that the invention is not confined to the exactfeatures shown, as various changes may be made within the scope of theclaims which follow.

In the drawings: Figure 1 is a diagrammatic view in side elevation ofthe novel apparatus; Figure 2 is a similar view in plan; Figure 3 is adiagrammatic view in side elevation of a specimen test body;

Figure 4 is a plotted data showing the relation between maximumamplitude ofv vibration andamount of unbalance;

Figure 5 is a similarly plotted data on a I scale one-tenth that ofFigure 4 with weights ten times as great;-

Figure 6 is a process chart for the determination of proper relativeangular positions of corrections;

Figures 7, 8 and 9 are plotted results of data obtained during threesuccessive operations of the apparatus, as, for example, when allfactors contributive to'the unbalance are unknown.

when rate of passage through the criti-- cal speed is definitelycontrolled and reabsence of such control is one of the chief reasonswhyconsistent results are not ob tainable with other appliances used in thepast, and for the discovery made by applicant that under properconditions there is a direct proportionality between the maximumamplitude of oscillation and the amount of unbalance. It is necessaryalso to the success of this process that damping resistance to vibrationof the supporting means be reduced to a relatively low value,

otherwise the proportionality between the amount of unbalance to bedetermined and the amplitude ofvibration does not exist. Failure toaccomplish this reduction of damping forces is another reason why suchamplitude measures as have been made heretofore cannot serve as a basisfor a systematic' process such as I have devised.

The maximum amplitude of vibration thatoccurs as the rotatingbody/passes through the critical speed, does not necessarily occur atthe exact instant ofsynchronism be tween the period of rotation of theBody and the period of free. oscillation, but it does occur in theneighborhood of this condition of synchronism and near the time whenthis condition is passed through. This maximum amplitude. undoubtedlyoccurs shortly after the instant of passing through critical speed andthat it may be an accurate measure of the unbalance of the rotatingbody, it is necessary that critical speed be passed through at a.certain, definite, slowly reducing or increasing rate.

When care is taken to cause the critical speed to be passed through at adefinite rate and to reduce the damping resistance to a relatively lowvalue, the correspondence between this maximum amplitude of vibrationand the amount of unbalance is very accurate as is demonstrated inFigures 4 and 5. In these figures, the abscissas indicate the amount ofunbalance of a rotating body in grammes, the ordinates indicate themaximum' amplitude in scale divisions as the rotating body passesthrough critical speed.

.The preotthat the maximum amplitude is proportional. to the amount ofunbalance lies in the fact that the points representing theseobservations lie on a straight line which passes through the origin.Figure 4 shows this correspondence when the amount of unbalance is verysmall and Figure 5 Showsthe ratio between the maximum amnlltude and theamount of unbalance as the same when unbalance is of conto be quiteaccurate. However; since indi-,

vidual observations show some slight differences, it is advisable whenextreme accuracy is desired not to trust to a single observation but tocause. the rotor to drift down through resonant. speed two or threetimes,.observ1ng the maximum amplitude of oscillation each time, andthen combine the observations by taking the average of the measuredvalues.

' The general manner in which this novel principle may be availed of is,to rotatably mount the body to be tested in bearings havv l ing aminimum of friction on a freely workmg or swinging supporting means. Theoscillatory movement of the supporting means is preferably againstspring tension.

Desirably this body is mounted on a sup porting means which remainsunchanged during the test, not only of a. given body, but also duringthe successive determinations of'all bodies of the same shape and dimensions, as, for example, during the run of a lot of the same quantityproduction. In such procedure, the critical speed is attained by havingthe body freely rotating in its support and by giving it an initialrotative rate in excess of the predetermined natural oscillatoryfrequency of the particular setup supporting means under the load of theonly may be quickly detected, but also, by

reference to a constant, the amount 'of the necessary corrective weightmay be rapidly and accurately ascertained. Further, the rapidascertainment of the point on the rotative unbalanced body at which suchcorrective weight must be aflixed can be had. An additional advantage ofthis novel process resides in the fact that a slight unbalance in arotative body may be measured while the body is rotated at a relativelylow rate of speed. For example, the supporting means may be so arrangedthat its natural vibration frequency is seventy-five or one hundredvibrations per minute, which readily per- 4 mits an accurate visualdetermination of the maximum amplitude of the vibration or oscillationinduced by the rotative body.

Any resilient support such as is commonly used in balancing machines andpossessing certain natural frequency of vibration when acted upon by aperiodic force of varying frequency, such as is produced by anunbalanced body rotating thereon, will re-act in accordance with theperiodic force to a markedly greater extent when the frequency of theperiodic force is. equal to the natural frequencyof the systemcomprising the body and its support. This marked increase of vibrationis called resonance and the speed of the body at which maximum vibrationwould occur if the speed were constant is the critical speed as hereindefined. When a body of relatively large amount of inertia revolvesfreely upon anti-friction v I bearings, such as ball bearings ofrefinedconstruction whlch are malntalned in a con stant state oflubrication, the rate of retardzition due to the slight friction ofbearin s and atmospheric resistance becomes precise y controlled in thatit is relatively slow, constant and repeatable. In the apparatus andprocess involved in .my invention, theresiliently pivoted supportingmeans are relatively free from damping resistance to vibra-- tion. Ifthe body is set into rotation at a higher; speed than the critical speedwhile saidsupporting means is locked at the cen-' tral or neutral pointof pivotal vibration, and if said lock isreleased without jar ordisturbance other than theunbalance of the revolvin body when the speedof rotation is only slightly above the critical speed, there will occuraphenomenon of beats, due to the small difference between the period ofrotation and the period of free vibration. The largest amplitude ofvibration which occurs during the beat at or following the criticalspeed is proportionate to the amount of unbalance to be determined inthe revolving body, and when so measured constitutes one means ofestablishing the amplitudes referred to in my process. Thischaracteristic form of vibration occurs only in apparatuses of the formof my invention, and differs fundamentally from the forced or partiallyresonant vibrations of other apparatuses heretofore used, where the bodyis revolved at an approximately constant speed or at' a roughly varyingspeed, which cannot be accurately repeated, by the application ofperiment may show them to become reduced.

obvious variation of this process would be. to cause the rotating bodyto pass through critical speed at a uniformly repeatable rate, butwithout reducing the damping resistance to vibration to a negligibleamount. In such case the observed amplitudes of vibration would not beproportional to the unbalance, but certain advantages of systematicprocedure would be secured.

It is to be understood that, while reference is herein made to themaximum ampli-- tude of, oscillation of the supporting means, referencecould as well be made to the maximum velocity of the supporting meansand which, a correction is to be applied-is no longer in the axis ofoscillatory motion, Thecorrection to be applied in t-lris'plane is nowdetermined and applied and balance can thus be completed withoutcalculations. Other methods in which the body is not mounted, asexplained above, withone of the arbitrarily chosen planes in the axis ofoscillation, require computations for the determination of thecorrection which is actually to be applied.

A still greater advantage arises if the body be mounted fordetermination of the first correction as just described, with one of thearbitrarily chosen planes in the axis of oscillation, and when thesecond correction is being determined, the second of the two arbitrarilychosen-planes is placed in the axis of oscillation of the rotative body.If this plan is followed, the second correction may be determinedwithout first applying the correction first determined. This is. a greatadvantage in quantity production since corrections may be determined andthe bodies marked for subsequent correction without the application ofany correction during the process of balancing.

An assemblage or set-up of apparatus adapted to carry out this novelprocess is shown in the drawings. The supporting means herein consistsof a substantially rectangular frame 1 carried by the two uprights orstandards 2. A bearing plate 3, preferably metallic, is secured to theupper face of each of the standards. The rotative body, a fly-wheel 4being here shown for sake of full and clear disclosure, is rotatablyborne by the frame. As here diagrammatically indicated, the shaft5 ofthe flywheel is rotatably mounted in antifriction bearings such asball-bearings 6 carried by the frame sides. to rock or oscillate on thestandards 2 and in this embodiment of the invention, the frame isprovided with knife edges 7. These knife edges are alined, i. e., are inthe same vertical plane, and such plane is at right angles to thevertical axial plane of the shaft 5 of the flj -wheel: 4. The plane ofthese knife edges 7 is not in the longitudinal axial plane of the framein order that the body maybe turned around so that adif- The frame 1 ismounted ferent radial plane of the body may be brought into coincidencewith the knife edge plane. This is desirable in order thatdeterminations of unbalance maybe made in two planes of the body.

In order that the amplitude of oscillation as well as the rate ofoscillation may be readily and accurately ascertained, a relative longarm 8 is rigidly secured to one end member of-the frame 1. This arm8,outwardly projecting'from the frame is preferably provided'with anindicator such as a pointer 9 which obviously has a greater lineartravel, in response to frame oscillattions, than any point on the frame.This pointer 9 is adapted to travel closely adjacent a scale 10 having aplurality of graduated unit notations thereon. Such notations are hereshown as superposed lines 11. This scale 10 is suitably adjustablysupported up-' on a rigid upright 12 positioned upon the floor or otherfoundation 13' as are the standards-2. A spring, such as a helicalspring 14 is mounted with its lower end 15 secured to the foundation 13and its upper end 16 secured to the arm 9 adjacent the pointer. Thespring 14 controls the oscillationof the arm 9 and different springs 14will variously affect the oscillation of the frame under the same load,hence, different oscillatory rates of the frame may be attained bychange of springs 14.

The methods of carrying out this novel process, when employing thisselected form of apparatus in which the critical speed is passed throughby retardation of a freely rotatable body, will now be described.

The particular. set-up or apparatus used is first calibrated forquantity balancing of duplicate parts such, for example, as thefly-wheel 4. A carefully dynamically balanced duplicate of the fly-wheel4 is drilled for instance with holes 17 (see Figure 3) each of which isat the same radial distance from the axis of the wheel 4. The holes 17are preferably drilled at definite positions being here shown asforty-five degrees apart.

The test wheel 4 is then accurately mounted upon the shaft 5 .and thewheel and shaft placed on the frame so that the shaft may rotate in theball bearings 6 and so that the plane of the vertical edge 18 of theflywheel 4 is in alinement'with'the plane of the knife edges?constituting the fulcrum of the frame. The frame, carrying this wheelmay be manually rocked and the natural rate of free oscillation of theapparatus noted. It should be noted that it is preferable to set up theapparatus so that a low rate'of natural oscillation is secured, such,for example, asa rate of one hundred -oscil lations per minute. a

If the wheel be in dynamic balance, the arm 9, held still at centerposition and then let free, will not oscillate when the wheel is rotatedin the frame. The scale is then adjusted and fixed on the upright 12 sothat the median line of the markings, i. e., the zero mark is in linewith the terminal of the pointer 11.. A11 arbitrary amount of weight isthen added in plane 19 by inserting it in any one of the holes 17. Thewheel 4 is then rotated slightly faster than thepredetermined-oscillatory rate of the frame, for example, about onehundred and ten'revolutions per-minute The wheel 4 .is then permittedfreely to rotate and the 7 slight frictional retardation only causes a'constant and uniform speed reduction so that the critical speed is veryslowly passed through. This gives full opportunity for the amplitude ofswing or oscillation of the 7 frame to be builtup and its exactmaximum Ps ed! lished.

' of scale division is known and the apparatus is calibrated and theproportional constant for this particular apparatus for this particularseries of relative bodies, is estab- It is evident that this passagethrough critical speed can be accomplished also by other means.Forexample, the wheel might be run at constant speedand the period offree oscillation changed or passed throu h the speed of rotation.This'can be done y varying the effective length of the. spring -14; orvar ing the momentof inertia of the frame 1 t thereon. a

The apparatus being calibrated, the furough the movement of a weightther steps of the process areeas follows:

The test duplicate wheel is removed and on'e of the unbalancedduplicates of the flywheel, such as the fly-wheel 4, is placed in theframe so that the plane of thevertical edge 18 of the wheel is in exactalinement with the plane of theknife edge 7 The unbalanced wheel 4 isthen freely rotated in the same manner as was the test duplicate. Themaximum amplitude on the scale 10 is observed and noted. The ratio orpropor 'tional constant (above described) multiplied by. the maximumamplitude will give the unt of correction to place in the plane 19 ofthe unbalancedwheel'.

The required amount of weight being de termined, this weight is thenplaced in any point in the circle 20 scribed on-the end surface of thewheelin this plane 19 Such circle is employed as it may be necessary toshift the weight and it is necessary to preserve the same radialdistance from the axis of the test Wheel. Upon positioning of the known,weight, the wheel is again freely rotated as before and reduction ofspeed permits passage through critical speed again. The maximumamplitude is again noted. From the relation between these two maxi- -mumamplitude readings, it ispossible to determine the amount of the anglethrough which the known weight should be moved. The direction in whichthis angle should be measured is then determined by shifting the weightthrough the required angle in either direction and rotating the wheelagain to determine whether it is or is not in balance;

that is, whether the weight was shifted in the right direction or in thewrong one. In either case, this third rotation .of the wheel determinesthe direction in which the angle should be measured. The relationsbetween various maximum amplitude readings have been plotted by theinventor hereof and are shown in the process chart disclosed in Figure6. The ratio between the second amplitude and the first amplitude will,by reference to the mathematically calculated process chart, give indegrees the angular error of weight positioning on the scribed circle.The corrective Weight is then accordingly fixed or marked.

The novel reference process chart (Figure '6) for the determination ofproper relative angular positions of corrections has been developed asfollows: The circle showing an gular positions in degrees is drawn-anddegrees spaced and marked thereon as shown. With true point at zerodegrees, the resultant forces have been figured and plotted fromconsideration oftwo equal unit forces acting at same radius at differentangles apart. The forces are opposite and equal at zero degrees andbalanced, and they pull in same direction at 180 degrees and unbalanceis doubled. This isa graphic representation of What is done inbalancinga rotative body when, after proper correction has been determined, it isapplied at different angular positions on said body. The plotting ofsaid resultant forces upon the different angle flines results in the-'outside trigonometric curve of the chart which is a function of theincluded angle ;--also, as calculated from unit forces it can be usedproportionally. Asmaximum amplitude of the arm 8 is accuratelyproportional to amount of unbalance, it is clear that the amplitudebefore correction was applied taken as the amplitude unit and the ratioof the second amplitude to same taken after correction was applied andreferred to the process chart, will give the included angle for properlyposi.

tioning the correction. This process chart system could be exemplifiedin other ways as for instance, other diagrams, or measuring dials, orinstruments.

The next step in the process consists in taking the wheel 4 out of theframe, turning and restoring it to the frame so that its shaft ends areinterchanged, so that, for example, the other vertical plane of the edge19 of the wheel is in the vertical plane of the knife-edges 7. The sameprocedure is repeated. The wheel is then rotated, the maximum amplitudenoted, weight determined, and position ascertained and correction markedor applied on that face of the wheel which does not contain'the knifeedge. The

wheel 4 is then corrected for both static and dynamic balance. When itis not convenient to place edge 19 into alinement with fulcrums 7the'correction in plane 19 must be fixed to body and then plane 18 movedinto convenient position out of alinement with fulcrums 7 whilemeasuring unbalance in 9 plane 18.

When nothing definite about particular body to be balanced is known, northe apparatus calibrated, the alternate or second process, which is aform of previous process is as follows:

Two planes of the body are selected for correction and the body or wheel4 is mountprocess, where nothing definite about the ed in the sameapparatus in the same way as before described with one of said planes inalinement with the axis of the pivotjs or fulcrums 7. The bodyis thenrotated and the maximum' amplitude of frame oscillation, the same asbefore described, noted as it passes through critical speed. The resultis laid out graphically on a system or process diagram as in Figures 7,8 and 9. The abscissae represent the angles at which correction has beenapplied and the ordinates corresponding amplitudes. Some definitecorrection is now applied to the body or Wheel in the other planeselected for correction at i a definite point in a definite circle asfor instance the circle 20, the body rotated and the resulting maximumamplitude observed same as before. The correction is then re-:

moved and then applied'to other quadrant or known points on same circle20, and the body rotated, maximum amplitude etc. noted in each instanceand theresults plotted and marked on system diagram Figure 7 and a'curve drawn joining them as shown. The

minimum of the curve. locates the point where correction is to beapplied. The distance A represents the amplitude after the correction isapplied and the distance B the amplitude before the correction-isapplied. The quotient of distance A- divided by the weight of thecorrection is, the proportional constant.

amount required for balance, the horizontal If the correction is smallerthan line representing the vno-correction amplitude lies midway betweenthe maximum and minimum of the curve. If the correction is greater thanrequired, the straight line lies below the middle, the proportionalconstant is used to compute the amount-to be added to, or substractedfrom the trial correction to produce balance.

When this process is gone through with and correction applied in oneselected plane,

amount of amplitude extra, or above the amplitude before applyingcorrection can be readily determined. j

It is also evident that by moving said corrective weight to pointsrequired around the circle, the maximum and minimum amplitudes can beascertain without laying out results graphically as in Figures 7 8 and9, and the amplitude A due to the correction applied can be ascertainednumerically from which the proportional constant is derived as before. I

Of fundamental importance in this second ing angles, as shown in Figures7, 8 and 9.

It is obvious that plats, diagrams or charts of this character or theirequivalents, or

equivalent numerical values, would be equally applicable to any form ofapparatus in which proportionality of vibration to the amount ofunbalance is obtained, and that the use [of the principles herebydisclosed in such manner would not depart from the fundamentals of thisinvention.

I claim' as my invention:

1. In the process of balancing a rotative body, the step which consistsin rotating the body upon a resilient support at a varying speed that isuniformly repeatable and that passes the critical speed and determiningand measuring the maximum amplitude of oscillation of said support.

' 2. In the process of balancing rotative bodies, the step whichconsists in rotating the body upon a resilient support which the bodyupon a resilient support at a decreasing speed that is uniformlyrepeatable and that passes the critical speed, and determining andmeasuring the maximum amplitude of oscillation 0 said support 4. In the'process of balancing rotative bodies, the step which consists inrotating the body upon a" resilient support which offers negligibledamping resistance to vibration at a decreasing speed that is uniformlyrepeatable and that passes the critical speed,'and determining andmeasuring the maximum amplitude of oscillation of said support. 1

5. In the process of balancing rotative bodies, the step Which'consistsin determining the amount of unbalance of the body by causing the sameto rotate. upon a re-' silient support at a varying speed that isuniformly repeatable and that passes critical speed, and determining andmeasuring the maximum amplitude of oscillation of said support. I 6. Inthe process of balancing rotative bodies, the step which consists indetermining the amount of unbalance of the body by causing the same torotate upon a resilient support which offers negligible dampingresistance to vibration, at a varying speed that is uniformlyrepeatableand that passes critical speed, and determining and measuring themaximum amplitude of osc1l-.

lation of said support.

7. The process of balancing rotative bodies, which consists in placingthe body in a swinging support having fulcrums at right angles totheaxis of rotation of the body, rotating the body upon said support ata decreasing speed that is uniformly re-' peatable and that passescritical speed, de termining and measuring the maximum amplitude ofoscillation, and determining therefrom the corrections necessary to bal-I ance the body.

8. The process of balancing rotative bodies which consists in mountingthe body with elastic restraint in pivotal supports at right angles toaxis of rotation of body; the rotating of the body above the point ofsynchronism between the rotation of the body and the oscillation ofsupports and body,

and the measurement of amount of unbalance by the measurement of themaximum oscillation of supports and body, while speed of rotation ofbody is being continuously reduced. I

9. The process of balancing a rotative body which consists in rotatingthe body upon a resilient support at a varying speed that is uniformlyrepeatable, to ascertain theoarnount of unbalance, selecting a tryoutpoint of application, of correction of the ascertained amount .andthendetermining the angle between the trial point of application ofcorrection of the amount and point where correction should'be a1;

to ascertain tlie amount of unbalance, s e-- lectinga trial point ofapplication of correction of the ascertained amount and theirdetermining the angle between the trial point of application ofcorrection of' the amount and the should be'applied. v

11. The process of balancing a rotative body :which consists in rotatingthe body upon a resilient support at a decreasing speed that isuniformly repeat-able, to, ascertain point where correction the amount.of imbalance, selecting a trial point of application of correction ofthe ascertained amount and then determining the angle between the trialpoint of application of correction of the amount and the point Wherecorrectionshould be applied.

12. Ina process of balancing rotative bodies, the step which consists'indetermin ing the angle between the point of application of a correctionand the point where said correction is required by comparison of thefirst determined correction with the amount of correction thendetermined, and reference to the mathematical resultantof two forces atdifferent angles with each other.

13. In a process of balancing rotative bodies, the step which consistsin determining the. angle'between the point of applicationof' acorrection and the'point where.

said correction is required by comparison of amplitudes, and referenceto the mathematical resultant of two forces at different angles witheach other.

14. A process of balancing rotative bodies which consists in correctingthe body in two selected planes at right angles to its axis of rotation,by rotatably mounting the body in I a fulcrumed frame; supporting theframe on fulcrums at right angles to' the axis of rotation of the body,the fulcrums being placed in one of said selected planes;'measuring theamount and position of correction required in the" other selected plane;then causing said fulcrums to be in said other selected plane; thenmeasuring the amount and position of correction required in said firstselected plane while thus out of the plane of the supporting fulcrum s.I p 15. A' process of balancing rotative bodies which consists incorrecting the. body in two selected planes at right angles to its axisof rotation, 'byrotatably mounting the body in a frame pivotallysupported in one of said selective planes; measuring and locating thecorrection required in the other selected plane; causing a pivotalsupport to be in said other selected plane; measuring and p the axis ofrotation of the body, the fulcrum points" being placed in one of saidselected planes of the body; then'rotating the body; 'then measuring andlocating the correction required in the other of said selected planesthen applying correction; then moving the body so that said points areout of the first selected plane; then rotating the body, and finallymeasuring and locating the correction-required in the first selectedplane.

17. A-process of balancing rotative bodies which consists in correctingthe body in two selected planes at right angles to its axis of rotationby rotatably mounting the body on supporting means pivotally in one ofsaid selected planes; rotating the-body, measuring and locatingthecorrecti'on'required in the other? of said selected planes; applyingthe correction; causing a pivoting point to be out of the first selectedplane; rotating the body, measuring and locating the correction requiredin said first selected plane.

18. The process of balancing rotative bodies which consists in placingthe body on a swinging support pivoted in alinement with one selectedplane of-the body and at right angles to the'axis of rotation of thebody; rotating the body; measuring and 10- eating the correctionrequired in another selected plane; then moving the body so" that thesecond selected plane is in alinement with said pivot or pivots;rotating the body;

and finally measuring and locating the correction required in the firstplane.

19. The process of balancing rotative bodies which consists incorrecting the body in two selected planes at right angles to its axisof rotation; placing the body in supports pivoted at rlghtangles td theaxis of rotation of the body and in one of said selected planes;rotating the body; measuring the amount and position of correction re- 7quired in the other selected plane; applying the correction; moving thebody in the supportsso said pivot or pivots are out of said firstselected plane; rotating the body; and finally measuring the amount andvposition oi correction required in said-first selected p ane.

20. The process of balancin 1 rotative bodies which consists in placingt e body in supporting means; mounting said supporting means on pivotsat right angles to the axis of rotation of the body and in one of twoselected planes of the body; rotating the body; measuring the amount andposition of plane; rotating the measuring the amount and position ofcorlected planes; applying the correction; moving the body in saidsupporting means sothat the pivots are out of said first selected body;and finally rection required in said first selected plane.

21. The process of balancing rotative bodies which-consists in mountinga body on a shaft; rotatably mounting the shaft in anti-frictionbearings supported by a frame swinging upon fulcrums at right angles tothe axis of rotation of the body and with the fulcrums in one plane ofsaid body; rotating the body to cause it to pass through critical speed;measuring the maximum amount of oscillation of the frame while passingthrough critical speed; determining and applying the requiredcorrection; moving the body so that the fulcrums are in a plane of saidbody other than first-mentioned plane; rotating the body to cause it topass through critical speed; measuring the maximum amount of oscillationof the frame while passing through critical speed; and

finally determining and applying the correction in said firSt mentiOnedplane putting bodyin complete static and dynamic balance.

22'. In the process of balancing a rotative body, the step that consistsin rotating the body upon a support and at a varying speed that isuniforml repeatable an that passes critical speed, 0 serving the maximumamplitude of vibration, and determining therefrom, through the describedlaw of proportionality between amplitude of vibration and unbalance, theunbalance of the body.

23. In the process of balancing a rotative body, the step that consistsin rotating the a body upon a support and at a varying speed that isuniformly repeatable and that passes critical speed, anddetermining, byapplication of the described law of proportionality between amplitude ofvibration and unbalance, the unbalance of the body.

24. In the process of balancing a rotative body, the step that consistsin rotating the body upon a support at a varying speed that is uniformlyrepeatable and that passes critical speed, and determining the unbalanceof the body by observing the maximum amplitude of vibration andcomparing the same with a fixed scale disclosing the proportionalitybetween maximum vlbration and unbalance. e

25. In a process of balancin rotative bodies,'calibrating the aparatusdiy revolving a body carrying a own weight in a known plane at aknown radius from the axis of rotation, measuring the maximum amplitudeof oscillation of apparatus and body while passing from above to belowcritical speed, while the body is being rotated upon a support at avarying speed that is uniformly repeatable and determining the relationbetween a unit of maxi-- mum amplitude and a unitof known weight.

26. In the process of balancing rotative bodies, measuring the amplitudeof oscilla tion of the body, while the body is being rotated upon asupport and passing through critical speed ata ratethat is uniformlyreipeatable, and determining by repeated trials and by reference to'themathematical resultants of two forces at different angles, the

, amount and position of correction necessary to place the body'inbalance.

27. In the process of balancing rotative bodies, measuring the amplitudeof oscillation of thebody, While the body is being rotated upon asupport Whichofl'ers negligible damping resistance to vibration, andWhile the body is passing through critical speed at a rate that isuniformly repeatable, and determining by repeated trials, and byreference to the mathematical resultants of two forces at differentangles, the amount 'and position of the correction necessary to placethe body in balance.

28. The process of balancing rotative bodies, which consists incalibrating the apparatus as to proportionality between amplitude ofvibration and amount of unbalbody, and the amount to be added to thebody to correct said unbalance, and then determining the position insaid body at which said correction must be made.

29. In a balancing device, the combination of a frame, pivotally mountedto vibrat'e, means for entirely supporting a body rotatably in aplurality of bearings on said frame, the frame, pivots and thesupporting means being arranged so'that two different planes of thebody, substantially at right angles to its axis of rotation, may succes-'sively lie in the perpendicular axial plane of said pivots, and meansto control the pe riod of vibration of the frame.

30. In a balancing device, the combination of a frame, meansrotatably'to mount a body in the frame in a plurality of bearings, sothat said body is entirely supported by said frame, the frame beingpivotally mounted to oscillate so that the pivotal axis thereof may besubstantially within a radial plane of the rotative body selected forapplication of balance correction.

BURT L. NEWKIRK.

